Hotel heir Charlie Denihan wasn’t alone Sunday when he died of an apparent overdose, his friends tell me.

The 28-year-old Ivy League graduate, whose father runs the Denihan Hospitality Group (which includes the James and the Mansfield hotels), had been partying with Sarah Walker, 23, a model/actress.

“I introduced him to Sarah last week, and she stuck around and we couldn’t get rid of her,” a photographer friend of Denihan told me.

“He said, ‘I like taming lions.’ She was with him all weekend. The last thing she said to me on Monday was that she woke up in his apartment and he was dead.”

Police said Denihan was found on Sunday at 7:30 p.m. in his Union Square apartment by a roommate. “Charlie didn’t have a roommate,” his friend said.

Walker, a stunning brunette who was once represented by Next Model Management, informed me via text message: “Out of respect for Charlie and his family, I will not be speaking with you . . . Please leave me and his family alone.”

Friends said half a dozen revelers had been in and out of the apartment over the weekend. They don’t believe that the crystal meth and GHB police found on the premises belonged to Denihan.

“I spent quite a few nights with Charlie and there is no way he was using GHB or meth,” another pal said. “He was a fun-loving guy who worked hard and partied hard. He was in great shape. This never should have happened.”